QBARS - v20n1 Comparative Hardiness of Some R. elliottii Hybrids

Comparative Hardiness of Some R. elliottii Hybrids
Cecil Smith, Aurora, Oregon

On November 11, 1956, we in the Northwest experienced a sharp frost, down to 15 degrees F. This was preceded by very mild weather. The loss to shrugs in general was great. Included were eighty-five seedlings of R. elliottii , among which were about seventy from the same seed flat from which came the late Del James' variety 'War Paint'.
In this area, R. elliottii makes a second, and sometimes a third, growth and comes into the winter soft. The writer has not observed this tendency to make a second growth in a number of its hybrids.
Last winter the temperature went to about 5 degrees F. in our garden with 10 to 20 mile winds. 'Leo' ('Britannia' x R. elliottii ) was not hurt. It bloomed normally. A group of seedlings of 'Mars' x R. elliottii were not damaged and bloomed well. They have never displayed any tendency to make a second growth.
Many of another group of seedlings of 'May Day' x R. elliottii showed leaf damage and some flower bud damage. About half of this group bloomed well, however. 'May Day' with the same exposure had all its bloom buds blasted and was almost completely defoliated.
'Barclayi' and 'Kiev' ('Barclayi' x R. elliottii ) are within 15 feet of each other. 'Barclayi' lost its bloom buds, was completely defoliated, and lost about half of its 1964 growth. 'Kiev' lost its flower buds, and some of the leaves were scorched. It grew normally in 1965, while 'Barclayi' made very short wood growths. A group of younger, un-bloomed plants of R. yakushimanum x R. elliottii were not damaged in any way.
R. elliottii , I believe, has the finest red truss of any rhododendron, species or hybrid. It transfers many of its good qualities to its hybrids and, I must say, some of its legginess in some crosses, as in the 'Mars' cross.